Light Pollution
Chapter
1
What is Light Pollution?
• Definition:– Alteration of natural light levels in the outdoor
environment owing to artificial light sources
• It also known as photo-pollution or luminous pollution
2
• Light pollution is a side-effect of urbanization
• It is most severe in highly industrialized, densely populated areas of:– North America– Europe– Japan– Major cities in the
• Middle East• North Africa
3
4
• Its sources include:– Building exterior and interior lighting– Advertising– Commercial properties– Offices– Factories– Streetlights– Illuminated sporting venues
5
Types of Light Pollution
• Following are the types of light pollution– Light trespass– Over-illumination– Glare– Light clutter– Sky glow
6
Light Trespass
Light trespass occurs when unwanted light enters one’s property
7
Over-illumination
Excessive use of light
8
Sky glow
The glow effect that you can see over populated areas
9
Light Clutter
Excessive groupings of lights
10
Glare
When there is an excess of contrast between dark and light areas in one’s field of view
11
Effects of Light Pollution
• Light pollution has effect on– Natural resources and Environment– Humans– Animals
12
• The Environmental Protection Agency says that– Most electricity is used for lighting is
produced with coal and oil
• The emissions of burning coal and oil include– Carbon dioxide– Sulfur dioxide– Nitrogen dioxide
Nat
ura
l Res
ou
rces
&
En
viro
nm
ent
13
• These gases then create– Green house gas melting polar caps, change in
weather pattern, stress on eco-system, increase in CO2
– Acid rain Toxic water, damages trees, stress on eco-system, increase in SO2 and NO2
– Smog Breathing problems, crops are damaged
• Moreover, much of the light produced is wasted into the environment
14
• Light pollution has adverse effects on humans– Lack of melatonin hormone
production by pineal gland in brain due to presence of light
Hu
man
s
• Melatonin hormone is produced at night, when there is complete darkness
– It has been shown to powerfully suppress tumor growth in the body.
– It has strong antioxidant effects. This hormone is also known to enhance healing and regenerative processes within the body.
– Research suggests that it may help strengthen the immune system.
– It helps initiate the sleep cycle. it is one of the greatest natural cancer remedies.
15
– Effect on circadian clock (24-hour day/night cycle)
• Leads to sleep disorder• Lower performance
– Increase eyesight problem in kids– Increase level of anxiety
• Suicide rates increase– Highest in Finland during 24-hour daylight in
summers
16
• Birds– At least, 100 million birds are killed
annually due to combination of• Disorientation due to artificial lighting• Bright light• Towers with blinking beacons
– Bi-annual migration of birds is also effected
• Use reflection of stars and moonlight to guide their way. However, due to sky glow birds are facing problems in finding their way
An
imal
s
17
• Insects– Any outdoor light is usually surrounded by
an assortment of insects because they are attracted to light.
• Insects will fly around from light to light gathering with other insects and are eventually blinded, exhausted or overheated to death
– Studies show that the average street lamp kills at least 150 insects each night it is lit.
• Multiply that by 365 and you get 54,750 insects killed by one lamp in a year.
18
– Lesser insects may sound good, but it has an adverse effect on the entire food chain
• The birds, bats, reptiles and frogs depend on these insects for survival
19
• Sea Turtles– Sea turtle eggs are buried in the beach by their
mothers and hidden for a period of time. – When they hatch, the hatchlings are supposed to
crawl towards the water by looking for the brightest horizon
– Use the reflection of moonlight and stars on the water or the reflection of the sun on the water.
– However, due to light pollution, instead of heading for the water, the hatchlings are disoriented and heading for the cities and die from either exhaustion, being hit by a car or other various deaths
20
How to Reduce Light Pollution?
• Following are the ways:– By keeping lights dim– Turn off unnecessary lights– Use proper fixtures, which direct light to
specific objects– Use light detectors or sensors
21